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how to avoid "color banding" "banding" and "posterization" ?

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  #11  
Old 05-10-2007, 04:19 AM
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Re: how to avoid "color banding" "banding" and "posterization" ?

swampy i also work on an imac 24" and a connected 20" apple cinema display, which is calibrated well. the imac is only for the palettes. the people who want to buy the images
report that banding in my images when we sent a few to them for inspection.

the banding usually appears quick as i relatively often work on beach images, the models are usually underdeveloped and the sun is very strong. banding appears in the sky when i remove the magenta from it to make it more moody.

i would like to know which number you mean in the levels window, the one below or the one in the middle on the left each...? (output or input)

do you set the black point for each image you work on, i guess, by moving the slider to 10 and not to 0, like its shown in my window, the number below. (outputlevels) (0 – 255)

thx
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Old 05-10-2007, 07:15 AM
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Re: how to avoid "color banding" "banding" and "posterization" ?

Pure, Are you shooting in RAW? Just curious.

Is it banding or luminance artifacting? I'm no photographer, but are you using any kind of filters in the strong sunny situations?

To set your black and white clipping points in Levels... go to the Levels Option button and set the b/w points there.
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Old 05-10-2007, 08:29 AM
TheVeed TheVeed is offline
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Re: how to avoid "color banding" "banding" and "posterization" ?

swampy and ant give excellent advice.

If banding is occurring because of a color move, sometimes it helps (like Ant has discussed) to bring noise into it.

What I do, is I'll add noise to the mask, which sometimes really helps. I usually add 4-10, but generally stay within 6-8, depending on the file size, then I use the Fade Filter and set it to Luminosity. That way, you only get the grain in the greys of the mask, which has worked well for me.

Try it out, see if it works.
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Old 05-10-2007, 02:35 PM
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Re: how to avoid "color banding" "banding" and "posterization" ?

wow thanks swampy
some more detailed questions if you like:

is it stored there in the levels options "forever" or do i have to change it
for every image? also, does it only affect when i do auto-correction, as there is written auto in the box ( i dont work with auto-corrections)

you have added 0.10 there. (why exactly that number please?) are these the 2 boxes i have to set to 8 or 10?
like someone mentioned before...i quote : "Check your levels dialog box under "Options". to see where you have black/white set for clipping. Most printers want at least .10% for each."


for the banding, i also added noise (gaussian at 3) today, and it helped i guess.

(yes i get raw images, i develop with phase one or CS2, sometimes i only get JPGs, but rarely, and the photographers are shooting with a H1 Hasselblad or Canon 1d, but i dont know if they use polarizers or UV-Filters, i guess not)
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Old 05-10-2007, 03:36 PM
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Re: how to avoid "color banding" "banding" and "posterization" ?

Pure

You will have an option when you change the levels options to save it as default and it will be there forever and all adjustment dialogs will adhear to your rules. I have .10 in there because it was recommended in some tutorial I saw long ago (could have been in a Kelby or Eisman book). It indicates 10%. Anywhere from 5-10% should be good. (PS understands percentages).
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Old 05-10-2007, 03:44 PM
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Re: how to avoid "color banding" "banding" and "posterization" ?

ah i see.
additionally, would it be possible to set these "black ink rule" as default in the PS color management setting?
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Old 05-10-2007, 04:09 PM
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Re: how to avoid "color banding" "banding" and "posterization" ?

Quote:
Originally Posted by Swampy View Post
Excuse me, Godmother?
My comment was ment for Ant
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  #18  
Old 05-10-2007, 06:56 PM
yuccaview yuccaview is offline
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Re: how to avoid "color banding" "banding" and "posterization" ?

Try some noise and a motion blur at 45 degrees or so, maybe in just the
channel that banded.
Don
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  #19  
Old 05-13-2007, 10:39 AM
cspringer cspringer is offline
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Re: how to avoid "color banding" "banding" and "posterization" ?

I have to make more corrections for people who use RAW and send me a psd because of the noise they introduce so be careful. Do you take a jpg and RAW image when shooting? How does the jpg look.
I sometimes get crazy banding when editing in aRGB mode and none at all when editing the same picture in sRGB.
Others have mentioned setting the white/black points. Google for instructions. You might ask the lab what settings they want.
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Old 05-17-2007, 08:01 AM
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Newbie Re: how to avoid "color banding" "banding" and "posterization" ?

could i ask for your opinion please, one more time:

http://i127.photobucket.com/albums/p...n/67c1e56d.jpg

http://i127.photobucket.com/albums/p...n/8dee2c90.jpg


this is one example of my current situation, which usually repeats the banding problem: i add new image-elements with lot of gradients (skys, landscapes, sundowns....) and get banding when using masks.

one before, one after.

(the "before" has some banding in the sky ONLY because it is a JPG quality 6, to upload better – neglect this please)

the retouched JPG has banding in the sky where there was no banding in the raw before. i worked with around 15 or 20 layers, color corrections, levels, and a new sky, which looks more dramatic.

putting the sky behind him, i did a very soft and gentle gradient in the mask of the new sky, to blend it into the old sky. also i added a layer filled with black, multiplied to add more deepness in the middle of the image. that caused a major banding, you see the lines, i guess. (this is a JPG 10 quality, so no JPG artifacts or JPG banding should be visible)

would you say it will be eliminated in print? i did some "add noise" after that, (2x 0,5 gaussian noise monochrome) but the banding was still there. maybe i should have done "add noise" in the mask of the sky?



thanks

Last edited by pure; 05-17-2007 at 03:28 PM.
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